server: drop the dropping trigger logic while creating/recreating an event trigger

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/4101 GitOrigin-RevId: 12a2736e4d88dfb8379cd54f4beaedac32795d7d
2024-09-19 06:28:39 +03:00 · 2022-04-01 16:08:33 +05:30 · 2022-04-01 16:08:33 +05:30 · 330f9b6e26
commit 330f9b6e26
parent 4189122a3d
3 changed files with 105 additions and 51 deletions
--- a/server/src-lib/Hasura/Backends/Postgres/DDL/EventTrigger.hs
+++ b/server/src-lib/Hasura/Backends/Postgres/DDL/EventTrigger.hs
@ -494,7 +494,7 @@ dropTriggerOp triggerName triggerOp =
    getDropFuncSql op =
      "DROP FUNCTION IF EXISTS"
        <> " hdb_catalog."
-        <> pgIdenTrigger op triggerName
+        <> unQualifiedTriggerName (pgIdenTrigger op triggerName)
        <> "()"
        <> " CASCADE"

@ -564,15 +564,26 @@ unlockEventsTx eventIds =

 ---- Postgres event trigger utility functions ---------------------

+-- | QualifiedTriggerName is a type to store the name of the SQL trigger.
+--   An example of it is `"notify_hasura_users_all_INSERT"` where `users_all`
+--   is the name of the event trigger.
+newtype QualifiedTriggerName = QualifiedTriggerName {unQualifiedTriggerName :: Text}
+  deriving (Show, Eq, Q.ToPrepArg)
+
+pgTriggerName :: Ops -> TriggerName -> QualifiedTriggerName
+pgTriggerName op trn = qualifyTriggerName op $ triggerNameToTxt trn
+  where
+    qualifyTriggerName op' trn' =
+      QualifiedTriggerName $ "notify_hasura_" <> trn' <> "_" <> tshow op'
+
+pgIdenTrigger :: Ops -> TriggerName -> QualifiedTriggerName
+pgIdenTrigger op = QualifiedTriggerName . pgFmtIdentifier . unQualifiedTriggerName . pgTriggerName op
+
 -- | pgIdenTrigger is a method used to construct the name of the pg function
 -- used for event triggers which are present in the hdb_catalog schema.
-pgIdenTrigger :: Ops -> TriggerName -> Text
-pgIdenTrigger op trn = pgFmtIdentifier . qualifyTriggerName op $ triggerNameToTxt trn
-  where
-    qualifyTriggerName op' trn' = "notify_hasura_" <> trn' <> "_" <> tshow op'

 -- | Define the pgSQL trigger functions on database events.
-mkTriggerQ ::
+mkTriggerFunctionQ ::
  forall pgKind m.
  (Backend ('Postgres pgKind), MonadTx m, MonadReader ServerConfigCtx m) =>
  TriggerName ->
@ -580,50 +591,51 @@ mkTriggerQ ::
  [ColumnInfo ('Postgres pgKind)] ->
  Ops ->
  SubscribeOpSpec ('Postgres pgKind) ->
-  m ()
-mkTriggerQ trn qt@(QualifiedObject schema table) allCols op (SubscribeOpSpec listenColumns deliveryColumns') = do
+  m QualifiedTriggerName
+mkTriggerFunctionQ triggerName (QualifiedObject schema table) allCols op (SubscribeOpSpec listenColumns deliveryColumns') = do
  strfyNum <- stringifyNum . _sccSQLGenCtx <$> ask
-  liftTx $
-    Q.multiQE defaultTxErrorHandler $
-      Q.fromText . TL.toStrict $
-        let -- If there are no specific delivery columns selected by user then all the columns will be delivered
-            -- in payload hence 'SubCStar'.
-            deliveryColumns = fromMaybe SubCStar deliveryColumns'
-            getApplicableColumns = \case
-              SubCStar -> allCols
-              SubCArray cols -> getColInfos cols allCols
+  let dbQualifiedTriggerName = pgIdenTrigger op triggerName
+  () <-
+    liftTx $
+      Q.multiQE defaultTxErrorHandler $
+        Q.fromText . TL.toStrict $
+          let -- If there are no specific delivery columns selected by user then all the columns will be delivered
+              -- in payload hence 'SubCStar'.
+              deliveryColumns = fromMaybe SubCStar deliveryColumns'
+              getApplicableColumns = \case
+                SubCStar -> allCols
+                SubCArray cols -> getColInfos cols allCols

-            -- Columns that should be present in the payload. By default, all columns are present.
-            applicableDeliveryCols = getApplicableColumns deliveryColumns
-            getRowExpression opVar = applyRowToJson' $ mkRowExpression opVar strfyNum applicableDeliveryCols
+              -- Columns that should be present in the payload. By default, all columns are present.
+              applicableDeliveryCols = getApplicableColumns deliveryColumns
+              getRowExpression opVar = applyRowToJson' $ mkRowExpression opVar strfyNum applicableDeliveryCols

-            -- Columns that user subscribed to listen for changes. By default, we listen on all columns.
-            applicableListenCols = getApplicableColumns listenColumns
-            renderRow opVar = applyRow $ mkRowExpression opVar strfyNum applicableListenCols
+              -- Columns that user subscribed to listen for changes. By default, we listen on all columns.
+              applicableListenCols = getApplicableColumns listenColumns
+              renderRow opVar = applyRow $ mkRowExpression opVar strfyNum applicableListenCols

-            oldDataExp = case op of
-              INSERT -> SENull
-              UPDATE -> getRowExpression OLD
-              DELETE -> getRowExpression OLD
-              MANUAL -> SENull
-            newDataExp = case op of
-              INSERT -> getRowExpression NEW
-              UPDATE -> getRowExpression NEW
-              DELETE -> SENull
-              MANUAL -> SENull
+              oldDataExp = case op of
+                INSERT -> SENull
+                UPDATE -> getRowExpression OLD
+                DELETE -> getRowExpression OLD
+                MANUAL -> SENull
+              newDataExp = case op of
+                INSERT -> getRowExpression NEW
+                UPDATE -> getRowExpression NEW
+                DELETE -> SENull
+                MANUAL -> SENull

-            name = triggerNameToTxt trn
-            qualifiedTriggerName = pgIdenTrigger op trn
-            qualifiedTable = toSQLTxt qt
-            schemaName = pgFmtLit $ getSchemaTxt schema
-            tableName = pgFmtLit $ getTableTxt table
+              name = triggerNameToTxt triggerName
+              qualifiedTriggerName = unQualifiedTriggerName dbQualifiedTriggerName
+              schemaName = pgFmtLit $ getSchemaTxt schema
+              tableName = pgFmtLit $ getTableTxt table

-            operation = tshow op
-            oldRow = toSQLTxt $ renderRow OLD
-            newRow = toSQLTxt $ renderRow NEW
-            oldPayloadExpression = toSQLTxt oldDataExp
-            newPayloadExpression = toSQLTxt newDataExp
-         in $(makeRelativeToProject "src-rsr/trigger.sql.shakespeare" >>= ST.stextFile)
+              oldRow = toSQLTxt $ renderRow OLD
+              newRow = toSQLTxt $ renderRow NEW
+              oldPayloadExpression = toSQLTxt oldDataExp
+              newPayloadExpression = toSQLTxt newDataExp
+           in $(makeRelativeToProject "src-rsr/trigger.sql.shakespeare" >>= ST.stextFile)
+  pure dbQualifiedTriggerName
  where
    applyRowToJson' e = SEFnApp "row_to_json" [e] Nothing
    applyRow e = SEFnApp "row" [e] Nothing
@ -645,6 +657,50 @@ mkTriggerQ trn qt@(QualifiedObject schema table) allCols op (SubscribeOpSpec lis
      | otherwise = Extractor sqlExp Nothing
    getAlias col = toAlias $ Identifier $ getPGColTxt (ciColumn col)

+checkIfTriggerExists ::
+  QualifiedTriggerName ->
+  QualifiedTable ->
+  Q.TxE QErr Bool
+checkIfTriggerExists (QualifiedTriggerName triggerName) table =
+  fmap (runIdentity . Q.getRow) $
+    Q.withQE
+      defaultTxErrorHandler
+      [Q.sql|
+      SELECT EXISTS (
+        SELECT 1
+        FROM pg_trigger
+        WHERE NOT tgisinternal
+        AND tgname = $1 AND tgrelid = $2::regclass
+        )
+     |]
+      (triggerName, qualifiedObjectToText table)
+      True
+
+mkTrigger ::
+  forall pgKind m.
+  (Backend ('Postgres pgKind), MonadTx m, MonadReader ServerConfigCtx m) =>
+  TriggerName ->
+  QualifiedTable ->
+  [ColumnInfo ('Postgres pgKind)] ->
+  Ops ->
+  SubscribeOpSpec ('Postgres pgKind) ->
+  m ()
+mkTrigger triggerName table allCols op subOpSpec = do
+  -- create/replace the trigger function
+  dbTriggerName <- mkTriggerFunctionQ triggerName table allCols op subOpSpec
+  -- check if the SQL trigger exists and only if the SQL trigger doesn't exist
+  -- we create the SQL trigger.
+  doesTriggerExist <- liftTx $ checkIfTriggerExists (pgTriggerName op triggerName) table
+  unless doesTriggerExist $
+    let sqlQuery =
+          Q.fromText $ createTriggerSQL dbTriggerName (toSQLTxt table) (tshow op)
+     in liftTx $ Q.unitQE defaultTxErrorHandler sqlQuery () False
+  where
+    createTriggerSQL (QualifiedTriggerName triggerNameTxt) tableName opText =
+      [ST.st|
+         CREATE TRIGGER #{triggerNameTxt} AFTER #{opText} ON #{tableName} FOR EACH ROW EXECUTE PROCEDURE hdb_catalog.#{triggerNameTxt}()
+      |]
+
 mkAllTriggersQ ::
  forall pgKind m.
  (Backend ('Postgres pgKind), MonadTx m, MonadReader ServerConfigCtx m) =>
@ -653,7 +709,7 @@ mkAllTriggersQ ::
  [ColumnInfo ('Postgres pgKind)] ->
  TriggerOpsDef ('Postgres pgKind) ->
  m ()
-mkAllTriggersQ trn qt allCols fullspec = do
-  onJust (tdInsert fullspec) (mkTriggerQ trn qt allCols INSERT)
-  onJust (tdUpdate fullspec) (mkTriggerQ trn qt allCols UPDATE)
-  onJust (tdDelete fullspec) (mkTriggerQ trn qt allCols DELETE)
+mkAllTriggersQ triggerName table allCols fullspec = do
+  onJust (tdInsert fullspec) (mkTrigger triggerName table allCols INSERT)
+  onJust (tdUpdate fullspec) (mkTrigger triggerName table allCols UPDATE)
+  onJust (tdDelete fullspec) (mkTrigger triggerName table allCols DELETE)
--- a/server/src-rsr/trigger.sql.shakespeare
+++ b/server/src-rsr/trigger.sql.shakespeare
@ -35,5 +35,3 @@ CREATE OR REPLACE function hdb_catalog.#{qualifiedTriggerName}() RETURNS trigger
    RETURN NULL;
  END;
 $$;
-DROP TRIGGER IF EXISTS #{qualifiedTriggerName} ON #{qualifiedTable};
-CREATE TRIGGER #{qualifiedTriggerName} AFTER #{operation} ON #{qualifiedTable} FOR EACH ROW EXECUTE PROCEDURE hdb_catalog.#{qualifiedTriggerName}();
--- a/server/tests-py/validate.py
+++ b/server/tests-py/validate.py
@ -270,7 +270,7 @@ def validate_gql_ws_q(hge_ctx, conf, headers, retry=False, via_subscription=Fals
    print(ws_client.ws_url)
    if not headers or len(headers) == 0:
        ws_client.init({})
-    
+
    if ws_client.remote_closed or ws_client.is_closing:
        ws_client.create_conn()
        if not headers or len(headers) == 0 or hge_ctx.hge_key is None: